Failed early pregnancy (sometimes termed embryonic demise) refers to the death of the embryo and therefore, miscarriage. The most common cause of embryonic death is a chromosomal abnormality.
On this page:
Radiographic features
Ultrasound
Findings diagnostic of pregnancy failure
crown-rump length (CRL) of ≥7 mm and no heartbeat on a transvaginal scan 3
mean sac diameter (MSD) of ≥25 mm and no embryo on a transvaginal scan 3
absence of embryo with heartbeat ≥2 weeks after a scan that showed a gestational sac without a yolk sac
absence of embryo with heartbeat ≥11 days after a scan that showed a gestational sac with a yolk sac
sac with no embryo and an MSD <12 mm on initial scan that fails to double in size on a scan ≥14 days later 2
sac with no embryo and an MSD ≥12 mm on initial scan with no embryo heart activity on a scan ≥7 days later 2
embryo (irrespective of crown-rump length) without cardiac activity on initial scan and on repeat scan ≥7 days later 2
cessation of a previously documented cardiac activity of embryo (irrespective of crown-rump length)
Findings suspicious but not diagnostic of pregnancy failure
crown-rump length (CRL) of <7 mm and no heartbeat
mean sac diameter (MSD) of 16-24 mm and no embryo
absence of embryo with heartbeat 7-13 days after a scan that showed a gestational sac without a yolk sac
absence of embryo with heartbeat 7-10 days after a scan that showed a gestational sac with a yolk sac
absence of embryo ≥6 weeks after last menstrual period
absence of embryo when amnion seen adjacent to yolk sac (empty amnion sign)
embryo present with amnion visible around it but no heartbeat (expanded amnion sign)
yolk sac that is separated from an embryo when CRL is ≤ 5 mm (yolk stalk sign)
small gestational sac in relation to the size of the embryo (<5 mm difference between mean sac diameter and crown-rump length)
enlarged yolk sac (>7 mm)
Practical points
When there are findings suspicious for pregnancy failure, follow-up ultrasonography at 7-14 days to assess the pregnancy for viability is generally appropriate.